Shield with continuously concave inner sidewall

ABSTRACT

A write element for magnetic recording includes a main pole and a shield. The main pole has first and second sides with respect to a down-track direction. The shield at least partially surrounds the main pole with a continuously concave inner sidewall. The angle between the inner sidewall of the shield and the direction of motion of the write element is greater than the angle between the sides of the main pole and the direction of motion.

SUMMARY

A shield with inner walls surrounds a main pole. The inner walls of theshield have wall angles with respect to a down track direction thatexceed the wall angles of the main pole with respect to a down trackdirection. One embodiment of the shield resembles a wine glass shapedcavity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a perpendicular magnetic recordinghead according to an embodiment.

FIG. 2 is an air bearing surface view of a writer pole and “wine glass”shaped trailing shield according to an embodiment.

FIG. 3 is a plot of effective magnetic write field as a function ofmagnetic write width for a writer pole trailing shield withtrapezoidal-shaped cavity and for the writer pole wine glass trailingshield cavity of FIG. 2.

FIG. 4 is an air bearing surface view of a writer pole and wine glasstrailing shield cavity according to an embodiment.

FIG. 5 is an air bearing surface view of a writer pole with wine glasstrailing shield cavity according to an embodiment.

FIG. 6 is an air bearing surface view of a writer pole with trailingshield cavity with greater wall angles according to an embodiment.

FIG. 7 provides a flowchart of an example magnetic element fabricationroutine carried out in accordance with various embodiments.

DETAILED DESCRIPTION

FIG. 1 is a cross sectional view of an example perpendicular writer 10in accordance with various embodiments, which includes main pole 12,return pole 14, and write coils 16. Conductive write coils 16 surroundback gap closure 17 that magnetically couples main pole 12 to returnpole 14. Perpendicular writer 10 confronts magnetic medium 18 at an airbearing surface (ABS) of main pole 12 and return pole 14. Main pole 12includes main pole body 20, yoke 21, and main pole tip 22. Yoke 21 iscoupled to an upper surface of main pole body 20. Main pole tip 22 has aleading edge 24 and a trailing edge 26. Main pole tip 22 is separatedfrom return pole 14 at the ABS by insulating material 28. Write gap 35is defined by the distance between leading edge 24 and return pole 14.

Magnetic medium 18 may include magnetically soft underlayer 32 andmagnetically hard recording layer 34. It should be noted that theconfiguration for perpendicular writer 10 is merely illustrative andmany other configurations may alternately be employed in accordance withthe present invention. For example, perpendicular writer 10 may includetrailing shields, side shields, or wrap around shields that absorb straymagnetic fields from main pole tip 22, magnetic side tracks on recordinglayer 34, and other sources, such as the trailing edge of return pole14, during recording. Trailing shield 36 is shown proximate insulatinglayer 28 that surrounds main pole tip 22 of perpendicular writer 10.

Magnetic medium 18 travels or rotates in a direction relative toperpendicular writer 10 as indicated by arrow A. To write data tomagnetic medium 18, an electric current is caused to flow throughconductive write coils 16, which passes through write gap 35, betweenmain pole 12 and return pole 14. This induces a magnetic field acrosswrite gap 35. By reversing the direction of the current throughconductive coils 16, the polarity of the data written to magnetic medium18 is reversed. Main pole 12 operates as the trailing pole and is usedto physically write the data to magnetic medium 18. Accordingly, it ismain pole 12 that defines the track width of the written data. Morespecifically, the track width is defined by the width of trailing edge26 of main pole tip 22 at the ABS. Main pole 12 may be constructed of amaterial having a high saturation moment such as NiFe or CoFe or alloysthereof. More specifically, in various embodiments the main pole 12 isconstructed as a lamination of layers of magnetic material separated bythin layers of nonmagnetic insulating material 28 such as, for example,aluminum oxide.

One embodiment is shown in FIG. 2, which is a schematic representationof an ABS view of perpendicular writer 110. As shown in FIG. 2, writer110 includes return pole 114, main pole 122, insulator 128, and trailingshield 136. Main pole 122 has a trapezoidal pole tip with leading edge124, trailing edge 126 and sides 140 and 142. In this embodiment, shield136 includes inner sidewalls 150 and 152, leading edge 154, trailingedge 156, throat sidewalls 162 and 164, and mouth sidewalls 166 and 168.Leading edge 154 preferably is located closer to return pole 114 than isleading edge 124 of main pole 122, wherein any stray field may beeffectively prevented from reaching the magnetic medium. Inner sidewalls150 and 152 of shield 136 may not be parallel to sides 140 and 142 ofmain pole 122. As one possible result, wall angles θ2 of shield 136 maybe larger than wall angles θ1 of main pole 122. The trapezoidal shape isnarrower at leading edge 124 than at trailing edge 126 to aid inpreventing skew related adjacent track interference during writing whilethe write head is located at inner and outer portions of a magneticdisc.

In writer 110, throat sidewalls 162 and 164 and mouth sidewalls 166 and168 are adjacent leading edge 154, thereby possibly minimizing magneticfield concentration in that vicinity during writing. The significance ofincreasing the wall angle and introducing throat sidewalls 162 and 164is that, as the size of main pole 122 decreases in response to a demandfor higher areal density recording, the effective writing field ofmagnetic writer 110 may significantly exceed the effective writing fieldof a writer with a main pole having identical dimensions with shieldwalls parallel to main pole walls 142. The shape of the cavity in shield136 surrounding main pole 122 in writer 110 resembles a wine glass. Thelength of main pole 122, L1, may be less than the length of shieldcavity L2 and spacing S1 toward the front of the cavity may be less thanspacing S2 at the back of the cavity.

To assess how shield shape impacts writing performance, a series ofcalculations were made of the performance of a writer having atrapezoidal shaped cavity with walls parallel to walls 140 and 142 andwriter 110 with a wine glass shaped cavity for a shield. Measuredvariables were main pole write width, write pole wall angles θ1, sideshield spacing, and side shield wall angles θ2. In the trapezoidalshaped cavities, θ1=θ2. The dimensions of main poles were the same inboth writer configurations.

Exemplary results of such calculations are shown in FIG. 3. In FIG. 3,the maximum effective write field H_(eff)(max) is plotted versus themagnetic writer width. The data represent a series of H_(eff)(max) forboth writer configurations with identical write current, main pole wallangle, and main pole writer width. The average results for a trapezoidalshaped cavity magnetic writer design with θ1=θ2 are given by curve A.The average results for wine glass writer design 110 are given by curveB. For each case studied in the simulation, the wine glass design gaveboth consistently higher effective writing fields at a given magneticwrite width and narrower magnetic write widths at the same write field.

FIG. 4 shows a schematic representation of an ABS view of an exampleperpendicular writer 110A, which also features a shield with a wineglass shaped cavity. In FIG. 4, elements of writer 110A that are similarto elements of writer 110 are designated with the same reference numberfollowed by the letter “A”. Thus, main pole 122A of writer 110A issimilar to main pole 122 of writer 110. In this embodiment, innersidewalls 150A and 152A, throat sidewalls 162A and 164A, and mouthsidewalls 166A and 168A of shield 136A are concave, further minimizingmagnetic field concentrations in the vicinity of the throat area definedby sidewalls 162A and 164A. Wall angles θ2 of sidewalls 150A and 152Amay be larger than wall angles θ1 of main pole 122A. Length L1A of pole122A may be less than length L2A of the shield cavity and spacing S1Atoward the front of the cavity may be less than spacing S2 at the backof the cavity. This design may result in greater effective magneticfields during writing due to the narrower magnetic footprint of pole122A at the ABS.

FIG. 5 is a schematic representation of an ABS view of perpendicularwriter 110B illustrating another embodiment of the invention featuring ashield with a wineglass shaped cavity. Perpendicular writer 110B issimilar to writers 110 and 110A, and similar elements are designatedwith the same reference number followed by the letter “B”. In thisembodiment, shield 136B completely surrounds writer pole 122B. In FIG.5, the cavity does not extend to leading edge 154B of shield 136B.Leading end wall 170B of the cavity is positioned near, but spaced fromshield leading edge 154B. Curved sidewalls 150B and 152B, throatsidewalls 162B and 164B, mouth sidewalls 166B and 168B and cavityleading end wall 170B resemble a wine glass. Length L1B of pole 122C maybe less than length L2B of the shield cavity and spacing S1B toward thefront of the cavity may be less than spacing S2B at the back of thecavity.

FIG. 6 is a schematic representation of an ABS view of perpendicularwriter 110C illustrating another embodiment of the invention. Writer110C is similar to writers 110, 110A, and 110B, and similar elements aredesignated with the same reference number followed by the letter “C”. Inthis embodiment, trailing shield 110C completely surrounds main pole122C and the cavity does not extend to leading edge 154C of shield 110C.Sidewalls 150C and 152C form wall angles θ2 that are larger than wallangles θ1 of main pole 122C. The cavity resembles a wine glass without astem. That is, the cavity resembles the bowl of a wine glass. Length L1Cof pole 122C may be less than length L2C of the shield cavity andspacing S1C toward the front of the cavity may be less than length S2Cat the back of the cavity.

Differences in the shape and dimensions of the trailing shield withrespect to the main pole dimensions are key parameters in defining themagnetic bit shape on the recording medium. The wine glass writer designmay allow the magnetic write width to be varied by the shield geometryas well as by the main pole geometry. As shown in FIG. 3, the magneticwriter width of any effective write field can be decreased by theinventive shield geometries disclosed herein. As a result, referring toFIG. 2, for instance, leading edge 124, trailing edge 126 and wallangles θ1 can be made smaller while pole 122 produces the same writefield. Another benefit is that trapezoidal main poles with smaller wallangles are easier to fabricate, thereby decreasing the manufacturingcosts.

Write pole fabrication by damascene processing is a fabrication method.Pole fabrication by damascene processing is described in commonly ownedU.S. Pat. No. 6,949,833 and patent application Ser. No. 12/491,898 andincorporated herein in their entirety by reference. FIG. 7 illustratesexemplary steps to form a pole in an insulator layer such as layer 128in FIG. 2. First, an insulator layer is formed on a substrate (Step200). The insulator layer is preferably aluminum oxide although otherinsulator materials known in the art such as SiOx, MgO, SiC, etc. may beused.

Next, a trench is formed in the insulator layer (Step 210). The crosssection of the trench is preferably trapezoidal as shown by pole 122 inFIG. 2. A seedlayer is then deposited on the walls and bottom of thetrench to assist in formation of pole 122 (Step 220). A seedlayer isnecessary to control the quality of subsequent layers deposited in thetrench and can be deposited by plating, sputtering, or other materialdeposition techniques. An electrically conducting seedlayer is necessaryif subsequent layers are to be deposited by electroplating.

A layer of magnetic material is then deposited on the seedlayer (Step230). As discussed earlier, NiFe, CoFe, or alloys thereof are preferred.The magnetic layer can be deposited by electroplating, sputtering, orother methods of material deposition. Laminated pole structures provideimproved write performance. The next step is to deposit a layer ofnonmagnetic material on the magnetic material (Step 240). Nonmagneticmaterials suitable for use as a spacer layer are tantalum, ruthenium,aluminum oxide, magnesium oxide, and others. In the next step, theprocess is repeated until the trench is filled and the pole is formed(Step 250). The process then proceeds to the next manufacturing cycle(Step 260).

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1. An apparatus comprising: a main pole having first and secondsidewalls with wall angle θ1 with respect to a down-track direction; anda shield at least partially surrounding the main pole, the shield havinga continuously concave inner sidewall spaced from the main pole andhaving a wall angle θ2 greater than angle θ1.
 2. The apparatus of claim1, wherein the main pole and shield are separated by an insulatingmaterial.
 3. The apparatus of claim 1, wherein the inner sidewall of theshield has a shape that resembles a wine glass.
 4. The apparatus ofclaim 1, wherein the inner sidewall of the shield is longer than thesidewalls of the main pole such that the inner sidewall extends past thesidewalls of the main pole.
 5. The apparatus of claim 1, wherein theinner sidewall of the trailing shield defines a throat region proximal aleading edge of the main pole.
 6. The apparatus of claim 5, wherein thethroat region of the shield further comprises throat and mouth that areeach continuously concave.
 7. The apparatus of claim 1, wherein theshield completely surrounds the main pole at an air bearing surface. 8.The apparatus of claim 1, wherein the main pole material is CoFe or NiFeor alloys thereof.
 9. The apparatus of claim 1, wherein the shieldmaterial is CoFe or NiFe or alloys thereof.
 10. A write head comprising:a main pole with an air bearing surface (ABS), the main pole having aleading edge, a trailing edge, and a first sidewall with wall angle θ1;and a shield having a continuously concave first inner sidewall thatsubstantially surrounds the main pole with a wall angle θ2 greater thanθ1, the first inner sidewall separated from the trailing edge of themain pole by a first distance and separated from the leading edge of themain pole by a second distance, smaller than the first distance, thesecond distance defining a throat region.
 11. The write head of claim10, wherein the main pole and trailing are separated by an insulatingmaterial.
 12. The write head of claim 10, wherein the first innersidewall of the trailing shield is longer than the at least one sidewallof the main pole.
 13. The write head of claim 10, wherein the firstinner sidewall of the trailing shield extends away from the main poletowards a return pole to define a mouth region.
 14. The write head ofclaim 13, wherein the mouth region is separated from the main pole by athird distance, less than the first distance and greater than the seconddistance.
 15. The write head of claim 10, wherein the shield has asecond inner sidewall having the wall angle θ1 and positioned to face anopposite side of the main pole.
 16. The write head of claim 10, whereinthe main pole material is CoFe or NiFe or alloys thereof.
 17. The writehead of claim 10, wherein the shield material is CoFe or NiFe or alloysthereof.
 18. A method of recording magnetic data comprising: writing toa medium with a main pole with first and second sidewalls with wallangle θ1 with respect to a down-track direction; shielding the main polewith a shield at least partially surrounds the main pole with acontinuously concave inner sidewall spaced from the main pole and havinga wall angle θ2 greater than angle θ1.
 19. The method of claim 18,wherein the inner sidewall of the shield approaches the main poletowards a leading edge of the main pole.
 20. The method of claim 18,wherein the shield defines a gap that has a uniform distance between themain pole and a trailing edge of the shield.